binutils/rename.c

/* rename.c -- rename a file, preserving symlinks.
   Copyright (C) 1999-2020 Free Software Foundation, Inc.

   This file is part of GNU Binutils.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
   02110-1301, USA.  */

#include "sysdep.h"
#include "bfd.h"
#include "bucomm.h"

#ifdef HAVE_GOOD_UTIME_H
#include <utime.h>
#else /* ! HAVE_GOOD_UTIME_H */
#ifdef HAVE_UTIMES
#include <sys/time.h>
#endif /* HAVE_UTIMES */
#endif /* ! HAVE_GOOD_UTIME_H */

#if ! defined (_WIN32) || defined (__CYGWIN32__)
static int simple_copy (const char *, const char *);

/* The number of bytes to copy at once.  */
#define COPY_BUF 8192

/* Copy file FROM to file TO, performing no translations.
   Return 0 if ok, -1 if error.  */

static int
simple_copy (const char *from, const char *to)
{
  int fromfd, tofd, nread;
  int saved;
  char buf[COPY_BUF];

  fromfd = open (from, O_RDONLY | O_BINARY);
  if (fromfd < 0)
    return -1;
#ifdef O_CREAT
  tofd = open (to, O_CREAT | O_WRONLY | O_TRUNC | O_BINARY, 0777);
#else
  tofd = creat (to, 0777);
#endif
  if (tofd < 0)
    {
      saved = errno;
      close (fromfd);
      errno = saved;
      return -1;
    }
  while ((nread = read (fromfd, buf, sizeof buf)) > 0)
    {
      if (write (tofd, buf, nread) != nread)
	{
	  saved = errno;
	  close (fromfd);
	  close (tofd);
	  errno = saved;
	  return -1;
	}
    }
  saved = errno;
  close (fromfd);
  close (tofd);
  if (nread < 0)
    {
      errno = saved;
      return -1;
    }
  return 0;
}
#endif /* __CYGWIN32__ or not _WIN32 */

/* Set the times of the file DESTINATION to be the same as those in
   STATBUF.  */

void
set_times (const char *destination, const struct stat *statbuf)
{
  int result;

  {
#ifdef HAVE_GOOD_UTIME_H
    struct utimbuf tb;

    tb.actime = statbuf->st_atime;
    tb.modtime = statbuf->st_mtime;
    result = utime (destination, &tb);
#else /* ! HAVE_GOOD_UTIME_H */
#ifndef HAVE_UTIMES
    long tb[2];

    tb[0] = statbuf->st_atime;
    tb[1] = statbuf->st_mtime;
    result = utime (destination, tb);
#else /* HAVE_UTIMES */
    struct timeval tv[2];

    tv[0].tv_sec = statbuf->st_atime;
    tv[0].tv_usec = 0;
    tv[1].tv_sec = statbuf->st_mtime;
    tv[1].tv_usec = 0;
    result = utimes (destination, tv);
#endif /* HAVE_UTIMES */
#endif /* ! HAVE_GOOD_UTIME_H */
  }

  if (result != 0)
    non_fatal (_("%s: cannot set time: %s"), destination, strerror (errno));
}

#ifndef S_ISLNK
#ifdef S_IFLNK
#define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK)
#else
#define S_ISLNK(m) 0
#define lstat stat
#endif
#endif

/* Rename FROM to TO, copying if TO is a link.
   Return 0 if ok, -1 if error.  */

int
smart_rename (const char *from, const char *to, int preserve_dates ATTRIBUTE_UNUSED)
{
  bfd_boolean exists;
  struct stat s;
  int ret = 0;

  exists = lstat (to, &s) == 0;

#if defined (_WIN32) && !defined (__CYGWIN32__)
  /* Win32, unlike unix, will not erase `to' in `rename(from, to)' but
     fail instead.  Also, chown is not present.  */

  if (exists)
    remove (to);

  ret = rename (from, to);
  if (ret != 0)
    {
      /* We have to clean up here.  */
      non_fatal (_("unable to rename '%s'; reason: %s"), to, strerror (errno));
      unlink (from);
    }
#else
  /* Use rename only if TO is not a symbolic link and has
     only one hard link, and we have permission to write to it.  */
  if (! exists
      || (!S_ISLNK (s.st_mode)
	  && S_ISREG (s.st_mode)
	  && (s.st_mode & S_IWUSR)
	  && s.st_nlink == 1)
      )
    {
      ret = rename (from, to);
      if (ret == 0)
	{
	  if (exists)
	    {
	      /* Try to preserve the permission bits and ownership of
		 TO.  First get the mode right except for the setuid
		 bit.  Then change the ownership.  Then fix the setuid
		 bit.  We do the chmod before the chown because if the
		 chown succeeds, and we are a normal user, we won't be
		 able to do the chmod afterward.  We don't bother to
		 fix the setuid bit first because that might introduce
		 a fleeting security problem, and because the chown
		 will clear the setuid bit anyhow.  We only fix the
		 setuid bit if the chown succeeds, because we don't
		 want to introduce an unexpected setuid file owned by
		 the user running objcopy.  */
	      chmod (to, s.st_mode & 0777);
	      if (chown (to, s.st_uid, s.st_gid) >= 0)
		chmod (to, s.st_mode & 07777);
	    }
	}
      else
	{
	  /* We have to clean up here.  */
	  non_fatal (_("unable to rename '%s'; reason: %s"), to, strerror (errno));
	  unlink (from);
	}
    }
  else
    {
      ret = simple_copy (from, to);
      if (ret != 0)
	non_fatal (_("unable to copy file '%s'; reason: %s"), to, strerror (errno));

      if (preserve_dates)
	set_times (to, &s);
      unlink (from);
    }
#endif /* _WIN32 && !__CYGWIN32__ */

  return ret;
}